The present invention relates in general to heat transfer mechanisms, and more particularly, to cooling apparatuses and methods for removing heat generated by a plurality of electronic devices. Still more particularly, the present invention relates to fluidic cooling apparatuses and methods for cooling a plurality of electronic devices.
The industry trend has been to continuously increase the number of electronic devices within a computing system environment. Compactness allows for selective fabrication of smaller and lighter devices that are more attractive to the consumer. Compactness also allows circuits to operate at higher frequencies and at higher speeds due to the shorter electrical connection distances in such devices. Despite these advantages, providing many electronic devices in a small footprint can create device performance challenges. One of these challenges is thermal management of the overall environment. Heat dissipation issues, if unresolved, can result in electronic and mechanical failures that will affect system performance, irrespective of the size of the environment.
In many computing environments, microprocessors continue to increase in performance, with the active circuitry of the microprocessor chip being driven to an ever smaller footprint, leading to ever higher heat loads and heat fluxes. Notwithstanding this, reliability constraints often dictate that operating temperature of the devices not exceed a known maximum value.
The existing art has struggled with designing high-performance cooling solutions that can efficiently remove this heat. Conventional cooling solutions depend on conduction cooling through one or more thermal interfaces to an air-cooled heat sink, possibly employing a spreader or vapor chamber. To increase the heat removal capability of air-cooled systems, greater airflow is typically needed. Unfortunately, providing greater airflow is not always possible. Many factors must be taken into consideration in providing ever greater airflow, among which are acoustic noise considerations, as well as power concerns.
As an alternative, liquid-cooling methods have recently been incorporated into certain designs. Various types of liquid coolants provide different cooling capabilities. For example, fluid such as refrigerants or other dielectric liquids (e.g., fluorocarbon liquids) exhibit lower thermal conductivity and specific heat properties compared with liquids such as water or other aqueous fluids. These dielectric liquids have an advantage, however, in that they may be placed in direct physical contact with electronic devices and their interconnects without adverse effects, such as corrosion or electrical short circuits. Other cooling liquids, such as water or other aqueous fluids, exhibit superior thermal conductivity and specific heat compared with dielectric fluids. Water-based coolants, however, must be kept from physical contact with electronic devices and interconnects, since corrosion and electrical short circuit problems are otherwise likely to result.